package com.idea.id_generate.service;

import com.idea.id_generate.model.VO.ResolvedIdVo;
import com.idea.id_generate.model.query.IdQuery;
import com.idea.id_generate.model.query.ResolveIdQuery;
import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Service;

@Slf4j
@Service
public class SnowFlakeService {
    /**
     * 起始的时间戳
     */
    private final static long START_STMP = 1480166465631L;

    /**
     * 每一部分占用的位数
     */
    private final static long SEQUENCE_BIT = 12; //序列号占用的位数
    private final static long MACHINE_BIT = 5;   //机器标识占用的位数
    private final static long DATACENTER_BIT = 5;//数据中心占用的位数

    /**
     * 每一部分的最大值
     */
    private final static long MAX_DATACENTER_NUM = -1L ^ (-1L << DATACENTER_BIT);
    private final static long MAX_MACHINE_NUM = -1L ^ (-1L << MACHINE_BIT);
    private final static long MAX_SEQUENCE = -1L ^ (-1L << SEQUENCE_BIT);

    /**
     * 每一部分向左的位移
     */
    private final static long MACHINE_LEFT = SEQUENCE_BIT;
    private final static long DATACENTER_LEFT = SEQUENCE_BIT + MACHINE_BIT;
    private final static long TIMESTMP_LEFT = DATACENTER_LEFT + DATACENTER_BIT;

    private long datacenterId;  //数据中心
    private long machineId;     //机器标识
    private long sequence = 0L; //序列号
    private long lastStmp = -1L;//上一次时间戳

    public void initData(long datacenterId, long machineId) {
        if (datacenterId > MAX_DATACENTER_NUM || datacenterId < 0) {
            throw new IllegalArgumentException("datacenterId can't be greater than MAX_DATACENTER_NUM or less than 0");
        }
        if (machineId > MAX_MACHINE_NUM || machineId < 0) {
            throw new IllegalArgumentException("machineId can't be greater than MAX_MACHINE_NUM or less than 0");
        }
        this.datacenterId = datacenterId;
        this.machineId = machineId;
    }

    /**
     * 产生下一个ID
     *
     * @return
     */
    public synchronized long nextId() {
        long currStmp = getNewstmp();
        if (currStmp < lastStmp) {
            throw new RuntimeException("Clock moved backwards.  Refusing to generate id");
        }

        if (currStmp == lastStmp) {
            //相同毫秒内，序列号自增
            sequence = (sequence + 1) & MAX_SEQUENCE;
            //同一毫秒的序列数已经达到最大
            if (sequence == 0L) {
                currStmp = getNextMill();
            }
        } else {
            //不同毫秒内，序列号置为0
            sequence = 0L;
        }

        lastStmp = currStmp;

        return (currStmp - START_STMP) << TIMESTMP_LEFT //时间戳部分
                | datacenterId << DATACENTER_LEFT       //数据中心部分
                | machineId << MACHINE_LEFT             //机器标识部分
                | sequence;                             //序列号部分
    }

    private long getNextMill() {
        long mill = getNewstmp();
        while (mill <= lastStmp) {
            mill = getNewstmp();
        }
        return mill;
    }

    private long getNewstmp() {
        return System.currentTimeMillis();
    }

    /**
     * 解析ID
     * @param resolveIdQuery 需要解析的ID信息
     * @return 解析后的ID信息
     */
    public static ResolvedIdVo resolveId(ResolveIdQuery resolveIdQuery){
        ResolvedIdVo resolvedId = new ResolvedIdVo();
        resolvedId.setId(resolveIdQuery.getId());
        resolvedId.setDataCenterId(getDataCenter(resolveIdQuery.getId()));
        resolvedId.setWorkerId(getWorkId(resolveIdQuery.getId()));
        return resolvedId;
    }
    /**
     * 获取当前ID生成周期内的增长序数
     * @param id 需要获取的ID
     * @return ID的增长序数
     */
    private static long getSequence(long id){
        return id - (id >> 12 << 12);
    }

    /**
     * 获取ID的机器号
     * @param id 需要获取的ID
     * @return ID所属的机器号
     */
    private static long getWorkId(long id){
        return (id >> 12) - (id >> 17 << 5);
    }

    /**
     * 获取ID的机器号
     * @param id 需要获取的ID
     * @return ID所属的机器号
     */
    private static long getDataCenter(long id){
        return (id >> 17) - (id >> 22 << 5);
    }

    public static void main(String[] args) {
        SnowFlakeService snowFlake = new SnowFlakeService();
        snowFlake.initData(2,3);

        long start = System.currentTimeMillis();
        for (int i = 0; i < 100; i++) {
            long id = snowFlake.nextId();
            System.out.println(id);
            long sequence = getSequence(id);
            log.info("sequence id is{}", sequence);
            long workId = getWorkId(id);
            log.info("work id is{}", workId);
            long dataCenterId = getDataCenter(id);
            log.info("data center id is{}", dataCenterId);

        }

        System.out.println(System.currentTimeMillis() - start);


    }
}
